1. Field of the Disclosure
The present invention relates to an implant for the refixation of the osteotomised or fractured trochanter major (greater trochanter), to a so-called trochanter retention plate, and to a method for the operative refixation of the osteotomised or fractured trochanter major, with a trochanter retention plate.
2. Related Art
Various access paths to the hip joint, amongst other things, with osteotomy and subsequent refixation of the trochanter major, have been developed since the widespread introduction of hip endoprosthetics in the fifties and sixties. The refixation of this important tendon for the musculus gluteus medius and musculus gluteus minimus as well as different outer rotators should be effected in an anatomical manner after the prosthesis implantation. Moreover, the refixation of this important tendon should withstand the tensile force of the abductors, which under certain circumstances may amount to threefold the body weight. Various techniques have been developed for this purpose. Amongst these are for example the cerclage techniques which function with wires or cables. These may be supplemented by additional implants. These designs achieve reposition and compression of the present fragments by way of tension banding/cerclage, over the osteotomy location/fracture location. An actual neutralisation of the abductor tension is effected either via a type of braces-cerclage, which is fixed on the proximal femur, or not at all. The implants serve for the fixation of the wires/cables on the cranial-lateral aspect of the trochanter major. A direct, stable fixation of the implants on the proximal femur is not effected.
A further technique uses plate-like implants having a tension band function, which are fixed with screws or cerclages on the lateral aspect of the proximal femur. The reposition and fixation of the trochanter major is effected mostly via prong-like run-outs of the plate-like implants, which either only hook into the trochanter or which run out in an arched manner over the trochanter. A fixation in the trochanter region is effected either only with prongs or with cerclages around the trochanter massif (calcar femoris), or with screws into the trochanter-major-fragment. The laterally lying plate-like implants which exclusively take up the load, require a stable, partly high-profile design, in order to withstand the abductor forces. The lateral position directly above the tuberculum innominatum may then lead to the irritation of the tractus iliotibialis, which must slide over this region. Moreover, with larger radii or with a course of the prong around the trochanter-major-fragment, there exists the danger of the arch-like prongs bending open, or, with osteoporotic bones, of the partly sharp-edged prongs cutting in. Another technique makes the use of implants which are fixed directly on the prosthesis body, on the intramedullary nail or on the dynamic hip screw (DHS). Many of the mentioned implants have not displayed an adequate stability in clinical and/or biomechanical studies, or many of the mentioned implants suffered material failure in the course of dynamic loading.